No-core Monte Carlo shell-model calculation for 10Be and 12Be low-lying spectra

摘要

The low-lying excited states of 10Be and 12Be are investigated within a no-core Monte Carlo shell-modeln(MCSM) framework employing a realistic potential obtained via the unitary correlation operator method. Thenexcitation energies of the 2+n1 and 2+n2 states and theB(E2; 2+n1,2n→ 0+ng.s.) value for 10Be in theMCSMwith a standardntreatment of spurious center-of-mass motion show good agreement with experimental data. Some properties ofnlow-lying states of 10Be are studied in terms of quadrupole moments,E2 transitions, and single-particle occupationnnumbers. The E2 transition probability of 10C, themirror nucleus of 10Be, is also presented with a good agreementnto experiment. The triaxial deformation of 10Be and 10C is discussed in terms of the B(E2) values. The removalnof the spurious center-of-mass motion affects various states differently: for instance, it has a negligible effect onnthe 2+n1 and 2+n2 levels of 10Be, while it leads to a significant and favorable shift for the 1−n1 level. It is suggestednthat the description of 12Be needs a larger model space as well as some other higher excited states of 10Be, as annindicator that these are dominated by intruder configurations.